U.S. home prices rose 8.3 percent in December compared with a year earlier, according to data Tuesday from CoreLogic, a real estate data provider. That is the biggest annual gain since May 2006. Prices rose last year in 46 of 50 states.

Foreclosure activity picked up by 4% in June, and economic problems which include unemployment and falling homes prices will drive it relentlessly higher. That's bad news for homeowners, but the ripple effect from foreclosures goes beyond their immediate problems, and it will get much worse.

Some recent reports on the real estate market show home prices starting to stabilize in many areas. Other data suggests the housing market has further to fall. But whichever direction the national numbers are heading, there are few tenets that smart buyers and sellers should always follow.